The automotive industry uses hoses for transporting refrigerants such as fluorohydrocarbons and chlorofluorohydrocarbons. There also has been a movement to use alternative refrigerants like carbon dioxide and propane which is creating a need for alternative hose materials. The hoses generally have a three-layer laminar construction consisting of an inner tube, an outer cover located radially outwardly of the inner tube, and a reinforcing fiber layer interposed between the inner tube and outer cover. Generally, the inner tube is formed of acrylonitrile-butadiene rubber (NBR) or chlorosulphonated polyethylene (CSM). The reinforcing fiber layer usually is a mesh structure formed by braided organic yarn such as polyester fiber, rayon fiber, or nylon fiber. The outer cover typically is formed of ethylene propylene diene rubber (EPDM) or chloroprene rubber (CR).
The known multi-layered hose has a high degree of flexibility. Because of this property of the rubber materials, the hose can be handled with ease. In addition, the hose is free from deterioration due to harmful metallic substances such as metallic ions and/or metal chlorides originating from metallic pipings used in a refrigerating or cooling circuit.
However, rubber materials generally tend to have high gas permeability, that is, low resistance to gas permeation. One attempt to improve resistance of conventional rubber hoses to refrigerant permeation is using nylon as one of the layers of the inner tube of the hose. Unfortunately, hoses with a nylon inner layer suffer from reduced flexibility. The nylon layer also is readily attacked by conveyed chemicals. I have found improved resistance to refrigerant permeation with my new barrier hose construction, as well as decreased leakage of refrigerants at the coupling/hose interface.